Mechanical
Problems - Case History 2 Pump Wear - Electric Submersible Pump (ESP) used for Artificial Lift in Oil Extraction |
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Test
Objective
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Nameplate
details The ESP was operating at a depth of 7500 feet ( 2286 m) in a well deviation of 45°. |
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Additional
Information The cost of a replacement in the offshore environment is very costly hence on-line monitoring to get an assessment of the unit's health is very desirable. Outages can be planned and pumping uptake can be redirected to other pumps to avoid a sudden failure of the faulty one (e.g. operate it on reduced load). The use of vibration monitoring is not practical due to the operating environment, depths at which the ESPs operate, etc. MCSA is much more applicable since the measurements can be taken top-side. |
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The difference (red) envelope between the two spectra taken at different times is shown in Figure p-5. Note that the magnitude of the 60 Hz component did not change since the motor was operating on full-load in both cases. This change occurred over a period of 4 months. There must be disturbances in the motor-pump rotor since there are new components induced around 60 Hz. The pumping process was not being performed efficiently and the unit was removed for inspection and overhaul. |
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Figure (p-6)
shows a photo of the faulty pump. The result shows there is potential for MCSA to be used for monitoring the health of ESPs. Trending of the current spectrum should be used to assess mechanical wear deterioration in the pump. |
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Expert
Comment |
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Diagnostics Ltd, |
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